Early childhood sleep quantity, but not caregiver-reported sleep problems, predicts impulse control in children at age 8 years

Short duration of sleep and poor sleep quality have been linked to poor attention and impulse control in children. We aimed to determine the longitudinal predictive value of sleep quantity and quality during early childhood on objective and caregiver-report measures of attention, impulse control, and executive function in children at age 8 years. We used data from the Health Outcomes and Measures of the Environment (HOME) Study, a pregnancy and birth cohort. Caregivers reported on their child's sleep at ages 2, 2.5, 3, 4, and 5 years. Analysis included 410 participants. We used longitudinal growth curve models of early childhood sleep patterns to predict neurobehavioral functioning at age 8 years. Sleep problems did not predict any of our outcome measures at age 8 years. Sleep duration trended shorter as children matured, so predictive models examined both intercept and slope. Children with the least decline in sleep duration across early childhood had fewer impulsive errors at age 8 years on a continuous performance test (unadjusted p = .013; adjusted p = .013). Children with shorter duration of sleep across early childhood had worse caregiver-reported behavioral regulation at age 8 years (unadjusted p = .002; adjusted p = .043). Neither sleep duration slope nor intercept predicted inattention or metacognitive skills at age 8 years (p > .05). Total sleep time across early childhood predicts behavior regulation difficulties in school-aged children. Inadequate sleep during early childhood may be a marker for, or contribute to, poor development of a child's self-regulatory skills.

Predictors for achieving optimal sleep in healthy children: Exploring sleep patterns in a sleep extension trial

STUDY OBJECTIVES

Earlier bedtimes can help some children get more sleep, but we don't know which children, or what features of their usual sleep patterns could predict success with this approach. Using data from a randomized crossover trial of sleep manipulation, we sought to determine this.

METHODS

Participants were 99 children aged 8-12years (49.5% female) with no sleep disturbances. Sleep was measured by actigraphy at baseline and over a restriction or extension week (1 hour later or earlier bedtime respectively), randomly allocated and separated by a washout week. Data were compared between baseline (week 1) and extension weeks only (week 3 or 5), using linear or logistic regression analyses as appropriate, controlling for randomization order.

RESULTS

One hour less total sleep time than average at baseline predicted 29.7 minutes (95% CI: 19.4, 40.1) of sleep gained and 3.45 (95% CI: 1.74, 6.81) times higher odds of successfully extending sleep by >30 minutes. Per standardized variable, less total sleep time and a shorter sleep period time were the strongest predictors (significant odds ratios (ORs) of 2.51 and 2.28, respectively). Later sleep offset, more variability in sleep timing and lower sleep efficiency also predicted sleep gains. The sleep period time cut-point that optimized prediction of successful sleep gains was <8 hours 28 minutes with 75% of children's baseline sleep in that range.

CONCLUSIONS

Children with a baseline sleep period time <8½ hours a night obtained the most sleep from earlier bedtimes maintained over a week, demonstrating experimentally the value of earlier bedtimes to improve sleep.

CLINICAL TRIALS REGISTRY

Australian New Zealand Clinical Trial Registry, ACTRN12618001671257, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=367587&isReview=true.

Lengthening sleep reduces pain in childhood arthritis: a crossover randomised controlled trial

OBJECTIVES

Juvenile idiopathic arthritis (JIA) is a common chronic childhood disease and chronic pain is a debilitating feature. A strong link has been shown between poor sleep and pain in JIA. However, the causal direction is unknown. This study's aim was to determine if, in adolescents with JIA, a recommended healthful sleep duration leads to reductions in pain when compared with the restricted sleep (RS) duration that is commonly seen.

METHODS

Patients with JIA (12-18 years old; pain score of ≥1 on a visual analogue scale) participated in a randomised, crossover sleep manipulation protocol. The 3-week protocol comprised a baseline week (BL), a week with healthy sleep duration (HSD; 9.5 hours in bed/night) and a RS week (RS; 6.5 hours in bed/night). After BL, participants were randomly assigned to either HSD or RS, and then crossed over to the other condition. Pain was self-assessed using the iCanCope with Pain app. We used Bayesian hierarchical models to estimate the effect of sleep duration on pain.

RESULTS

Participants (n=31; mean age=15.0±1.8 years) averaged 1.4 (95% credible interval (CrI) 1.2-1.6) more hours of sleep per night during HSD relative to RS. Compared with RS, HSD resulted in a favourable effect on pain scores (OR 0.61, 95% CrI 0.39-0.95).

CONCLUSION

It is possible to have adolescents with childhood arthritis get a healthier sleep duration, and this longer sleep results in reduced pain. These findings complement prior correlational studies and confirm a causal relationship between reduced sleep duration and increased pain.

TRIAL REGISTRATION NUMBER

NCT04133662.

0286 Presence and Potential Impact of Demographically Based Attrition in Pediatric Sleep Manipulation Research

Introduction

Pediatric sleep manipulation studies have mostly enrolled youth from dominant-culture, higher-income families. Studies with more diverse samples have been underpowered to detect differential attrition and demographic effect moderators. Here we pool data from two adolescent sleep manipulation protocols in a Midwest US city to better examine demographic differences in attrition rates and effect sizes.

Methods

Samples were pooled from studies detailed in Beebe et al. (2017; SLEEP, zsw035) and Duraccio et al. (2021; JSR, e13054). Both involved a sleep stabilization week, followed by 5-night periods of sleep restriction (6.5 hours/night in bed) and healthy sleep (9.5-10 hours/night in bed) in randomized counterbalanced order. Primary caregivers and 14-17 year-old adolescents each completed attention and sleepiness questionnaires for both conditions. Here we compare adolescents who were caregiver-identified as Black vs. White, the two largest local racial groups. Caregivers also reported their own education, family income, and household structure (single- vs. two-parent). Non-parametric tests looked for differential attrition and MANCOVA tested for racial differences in effects.

Results

Of the 257 initially enrolled, Black adolescents and those from households with one parent, lower income, or lower caregiver education were differentially lost to attrition (all p&lt;.001), even though the racial makeup of the final sample approximated the regional population (36% Black, 64% White). In the final sample, Black and White youth were equally able to change their sleep (p&gt;.90). Manipulation effects were significantly smaller for Black than White adolescents for inattention (self-report p=.026; parent-report p=.017) and sleepiness (self-report p=.002, parent-report p&lt;.001), but these differential effects were non-significant after controlling for family income, household structure, and caregiver education (p&gt;.05).

Conclusion

Even when a final study sample seemingly approximates the diversity of the local population, differential attrition may affect results. In this case, it superficially appeared that being in a non-dominant group (self-identified Black) was protective against the impact of short sleep. However, this effect disappeared after controlling for demographic risk factors. Participation in sleep manipulation studies can be challenging, so families facing higher burdens may need more support; otherwise, only the most resilient of those families may succeed, which could distort findings.

Support (If Any)

NIH (R01HL120879, R01HL092149)

0189 High Levels of Sleep Disturbance across Early Childhood Increases Cardiometabolic Disease Risk Index in Early Adolescence: Longitudinal Sleep Analysis Using the HOME Study

Introduction

Sleep is a predictor of cardiometabolic disease (CMD) risk, and new evidence links early childhood sleep to later CMD risk. This study examines the impact of early childhood sleep duration, bedtime timing, and sleep disturbance on a CMD risk score in early adolescence.

Methods

Within the Health Outcomes and Measures of Environment (HOME) Study, a prospective pregnancy and birth cohort study, we assessed sleep patterns among 346 children using the Children’s Sleep Habits Questionnaire from ages 2 to 8 years. We calculated cardiometabolic risk scores ate age 12 for 183 of these children from visceral adiposity area, blood pressure, fasting serum triglyceride, high density lipoprotein, leptin, and adiponectin concentrations. We used a group-based semi-parametric mixture model to identify distinct trajectories in sleep duration, bedtime timing, and sleep disturbance for the entire sample. We then examined the associations between sleep trajectories and CMD risk score using general linear models for children with a CMD risk score, using both an unadjusted model (no covariates) and an adjusted model (adjusting for child pubertal stage, child sex, duration of breastfeeding, household income, and maternal education).

Results

Three sleep trajectories emerged for bedtime timing (late timing, medium timing, and early timing) and for sleep disturbance (high, medium, and low), and two for sleep duration (high and low). In the unadjusted model, we found significant differences in CMD risk scores by trajectories of sleep disturbance. Children in the ‘high’ trajectory had higher CMD risk scores (Least Square Mean=1.51; 95% CI: 0.39, 2.64) than those in the ‘low’ trajectory (Least Square Mean =-0.51; 95% CI: -1.16, 0.15; p=.002) and ‘medium’ trajectory (Least Square Mean=-0.15; 95% CI: -1.14, 0.85; p=.03). These findings only approached significance after adjusting for covariates. No significant differences in CMD risk were observed for bedtime timing or total sleep time trajectories in the unadjusted or adjusted models.

Conclusion

In this cohort, parent-reported sleep disturbance in early childhood was associated with more adverse cardiometabolic profiles in early adolescence. Our findings suggest that trials to reduce CMD risk via sleep interventions – which have been conducted in adolescents and adults – may be implemented too late.

Support (If Any)

National Institute of Environmental Health Sciences grants PO1 ES11261, R01 ES014575, R01 ES020349, R01 ES027224, R01 ES025214.

Changes in Adolescent Meal Patterns and Processed Food Consumption Following Sleep Restriction: Results From a Randomized Crossover Trial

Objectives

To evaluate if sleep restriction influences 1) meal frequency and late evening food consumption; and 2) intake of ultra-processed foods in male and female adolescents.

Methods

A total of 92 healthy adolescents 14–17 years old participated in a cross-over experimental sleep protocol, comparing two conditions, each lasting 5 nights: healthy sleep (HS, 9.5 h/night) and shortened sleep (SS, 6.5 h/night). The order of conditions was randomly counterbalanced, and there was a washout period of 2 days between conditions. The study team conducted 24-h dietary recalls on 3 randomly selected days during each sleep condition. For objective 1, we used the timestamps of the meals in each dietary recall to determine number of eating occasion in 24 h, number of eating occasion after 8PM, and kilocalories consumed after 8PM. For objective 2, we used the Nova food classification system to determine kilocalories and % of kilocalories consumed from ultra-processed foods (UPF) over 24 hours and after 8PM. We used general linear model analysis to compare these outcomes between HS and SS conditions. We also explored the moderating impact of individual and experimental factors, including family income and participant age, sex, age- and sex-adjusted body mass index, and the order in which they had the sleep conditions.

Results

There was no significant difference in number of eating occasions in 24 h across experimental conditions (SS = 4.2, HS = 4.1, P = .25). After 8PM, there was a significantly greater number of eating occasions (0.87 vs. 0.59, P &lt; .001) and higher kilocalorie consumption (354 vs. 223, P &lt; .001) during SS than HS. There was no difference in daily UPF kilocalorie consumption across conditions (SS = 1439, HS = 1397, P = .38), but UPF kilocalories after 8PM were significantly higher during SS than HS (291 vs. 172, P &lt; .001). These findings did not vary based on our exploratory individual and experimental factors.

Conclusions

Adolescents who are sleep restricted are more likely to eat more frequently, consume greater kilocalories, and eat highly processed foods after 8PM. Considering that these findings were not observed across the entire day, our findings suggest that sleep restriction may most negatively influence dietary patterns in the late evening.

Funding Sources

NIH.

581 Impact of Weight on Insomnia Severity, Sleep Quality, and Insomnia Improvement in a Clinically Referred Pediatric Sample

Introduction

Children with overweight/obesity are more likely to have shortened sleep, though little is known about the role of weight status in insomnia severity, sleep quality, and sleep hygiene in clinically referred youth.

Methods

A total of 1133 children (43.7% female) presented to a Pediatric Behavioral Sleep Medicine Clinic for insomnia. At the initial evaluation, caregivers of children ages 2–10.9 years (N = 744) completed the Pediatric Insomnia Severity Scale (PISI) and the Children’s Sleep Habits Questionnaire (CSHQ); adolescents ages 11–18 years (N = 389) completed the PISI, the Adolescent Sleep Hygiene Scale (ASHS), and the Adolescent Sleep Wake Scale (ASWS). The PISI was completed during at least one Pediatric Behavioral Sleep Medicine visit subsequent to evaluation and initiation of treatment. Patient height and weight, objectively measured within 3 months of the initial evaluation, was used to determine sex-adjusted body mass index z-scores (BMIz). Hierarchal linear regression models were used to determine the impact of BMIz on baseline PISI insomnia severity scores, and CSHQ, ASHS, and ASWS total scores, after covarying for income. Repeated-measures general linear modeling was used to determine whether weight status moderated improvement in insomnia severity over time, covarying for income.

Results

For children (ages 2–10.9), weight was not associated with baseline insomnia severity (p=.62) or predictive of insomnia improvement following behavioral sleep medicine intervention (p=.71), though higher weight predicted poorer parent-reported sleep quality (p=.006). For adolescents (ages 11–18), higher weight was predictive of higher baseline insomnia severity (p=.026), though did not predict insomnia improvement over time (p = .86); higher weight was also predictive of poorer sleep hygiene (p&lt;.001) and worse sleep quality (p=.03).

Conclusion

Initial insomnia severity and subjective sleep quality may be worse for youth of higher weight, particularly for adolescents; these findings increase our understanding of how and when overweight/obesity negatively impacts sleep. Fortunately, youth with higher weight respond equally well to pediatric behavioral sleep medicine interventions as their lower-weight peers, suggesting that these interventions need not be modified based on patient weight.

Support (if any)

Cincinnati Children’s Hospital Medical Center Division of Behavioral Medicine and Clinical Psychology’s Research Funds

132 Impact of Experimentally Shortened Sleep on Meal Timing in Adolescents

Introduction

Short sleep increases the risk for obesity in adolescents. One potential mechanism relates to when eating occurs, rather than what or how much is eaten. This study investigated the impact of shortened sleep on meal timing and late evening eating in adolescents.

Methods

93 healthy 14- to17-year-olds (62% female) completed a within-subject counterbalanced experimental sleep manipulation, engaging in shortened sleep (SS; 6.5 hours/night in bed) or healthy sleep (HS; 9.5 hours/night in bed), each for five nights, with order randomized. Sleep timing was verified through wrist-worn actigraphy. During each sleep period, adolescents completed 2-3 dietary recalls. Repeated-measure T-tests assessed the sleep manipulation effect on averaged times of the first and last eating episode, number of eating episodes after 8:00pm, and range of the daily eating period.

Results

Youth averaged 2.2 hours/night longer sleep during HS than SS (p&lt;.001). The timing of the first eating episode was similar across conditions, relative to the clock (SS=08:51, HS=08:52) and to time since waking (SS=1.8hr, HS=1.9hr). The timing of the last eating episode averaged later on the clock during SS (20:34) than HS (19:38; p&lt;.001), resulting in a longer eating period (SS=11.7hr, HS=10.8hr, p&lt;.001). Youth averaged more eating episodes after 8:00pm during SS (0.87) than HS (0.59, p&lt;.001). The gap between last eating episode and sleep onset was larger in SS (4.1hr) than HS (2.8hr; p&lt;.001). Notably, on average, adolescents last eating episodes during SS (20:34) were earlier than sleep onset in either condition, and were even 2 hours earlier than when they fell asleep during HS (M=22:30). In exploratory analyses, these effects did not systematically vary by experimental order of the sleep conditions, family income, or participant age, sex, or norm-referenced body mass index.

Conclusion

Shortened sleep resulted in adolescents eating later and lengthening the daily period of time in which they ate, despite typically stopping eating well before sleep onset during healthy sleep. Late evening eating and long daily eating periods have been strongly associated with weight gain, which may help explain the link between shortened sleep and increased obesity risk in adolescents.

Support (if any)

R01HL120879

0408 Myths About Infant, Child, and Adolescent Sleep: Addressing False Beliefs That Hinder Sleep Health During These Crucial Developmental Stages

Introduction

Sleep is vital for healthy development from infancy through adolescence. Despite its importance, false beliefs that conflict with scientific evidence (myths) may be common among caregivers and impair sleep health during these crucial stages.

Methods

Researchers compiled a list of potential myth statements using internet searches of popular press and scientific literature. We utilized a Delphi process with experts (n=12) from the fields of pediatric, sleep, and circadian research and clinical practice. Selection and refinement of myths by sleep experts proceeded in three phases, including: focus groups (Phase 1); email-based feedback to edit, add, or remove myths (Phase 2); and closed-ended questionnaires (Phase 3) where experts rated myths on two dimensions: (1) falseness and (2) public health significance using 5-point Likert scale: 1 (“not at all”) to 5 (“extremely false/important”).

Results

Thirty-two sleep myths were identified across three developmental categories: infant (14 myths), child (6 myths), and adolescent (12 myths). Mean expert ratings illuminated the most pressing myths in each developmental category: infant sleep (“Sleep training causes psychological harm, including reduced parent-child attachment:” falseness =4.7, s.d.=0.7; public health significance=4.0, s.d.=1.1); child sleep (“Heavy, loud snoring for my child means he’s sleeping deeply:” falseness=4.8, s.d.=0.6; public health significance=4.7, s.d.=0.7), and teenager sleep (“Falling asleep in class means your teenager is lazy and not motivated:” falseness=4.8, s.d.=0.5; public health significance=4.3, s.d.=0.8).

Conclusion

The current study identified commonly-held myths about infant, child, and adolescent sleep that are not supported by (or worse, counter to) scientific evidence. If unchecked, these myths may hinder sleep at a critical developmental stage. Future research may include public health education to correct myths and promote healthy sleep among infants, children, and teenagers.

Support

5T32HL007901

0269 Restricting Sleep Increases Teens’ Sedentary Behavior Without Impacting Moderate to Vigorous Physical Activity

Introduction

Short sleep duration has been linked to obesity risk in adolescence. However, most research has focused on potential changes in appetite/intake, rather than physical activity or sedentary behaviors. It remains unknown if, in the daily lives of adolescents, sleep restriction increases moderate- to-vigorous physical activity (e.g., by providing more time for it) or discourages such activity (in favor of sedentary behaviors). This was the first study to use gold-standard objective measures to assess cause-and-effect relationships between sleep duration and the resulting activity levels of adolescents in the naturalistic environment.

Methods

N=104 healthy teens (ages 14–18) completed the 3-week within-subjects crossover sleep manipulation experiment during the summer. Following a 7-night a sleep stabilization week, teens were randomly assigned to 5 nights in Short Sleep (6.5hrs sleep opportunity) or Healthy Sleep (9.5hrs sleep opportunity). Following a 2-night “washout” period, they crossed over to the alternate sleep condition. Throughout the study, they wore validated waist-worn accelerometers to objectively measure sedentary and physical activity levels, and wrist-worn actigraphs to confirm adherence to their sleep condition.

Results

When in Short Sleep (vs. Healthy Sleep), teens on average slept 112 minutes less (p&lt;.0001, d=1.72) per wrist actigraphy. Waist-worn accelerometers reflected 99 more minutes in sedentary behavior (p&lt;.0001, d=.97), and 16 more minutes in light physical activity (p=.002, d=.31) during short sleep. Teens did not differ in moderate-to-vigorous physical activity between conditions (p=.95, d=.03).

Conclusion

Among healthy adolescents, a realistic dose of sleep restriction did not affect moderate-to-vigorous physical activity levels, but did sharply increase time in sedentary behavior. Given the negative weight and health consequences of sedentary behavior, these results have practical implications for obesity prevention/intervention efforts. They suggest that extending teen sleep may neither encourage nor discourage healthy physical activity, but may help curb unhealthy behaviors (e.g., sedentary behavior).

Support

R01 HL120879

Brain gray matter volume differences in obese youth with type 2 diabetes: a pilot study

BACKGROUND

Adults with type 2 diabetes (T2D) have significantly lower gray matter volume (GMV) compared to healthy peers. Whether GMV differences exist in youth with T2D remains unclear. Thus, we compared global and regional GMV between obese youth with T2D with age, race and sex similar healthy controls.

METHODS

In a cross-sectional study, 20 obese youth with T2D underwent T1-weighted brain magnetic resonance imaging (MRI). Comparisons were made to 20 age, race and sex similar controls. Differences in global and regional GMV between groups were identified using voxel-based morphometry (VBM).

RESULTS

Youth with T2D had a significantly lower global GMV-to-intracranial volume ratio (0.51±0.02 in T2D vs. 0.53±0.02 in controls, p=0.02, Cohen's d=0.85). There were 14 regions where GMV was significantly lower in the T2D group, and nine of these were found in either the temporal or occipital lobes. There were six regions with increased GMV in T2D. All regional differences were significant at p<0.05 after adjusting for multiple comparisons.

CONCLUSIONS

Results from this pilot study show obese youth with T2D have significantly lower global GMV and regional GMV differences, when compared to their age, race and sex similar peers. Future work is needed to determine whether these brain findings are a direct result of adolescent-onset T2D.

The Development of a Clinically Relevant Sleep Modification Protocol for Youth with Type 1 Diabetes

Findings from type 2 diabetes research indicate that sleep is both a predictor of onset and a correlate of disease progression. However, the role sleep plays in glucose regulation and daytime functioning in youth with type 1 diabetes mellitus (T1DM) has not been systematically investigated. Nonetheless, preliminary findings have supported that various sleep parameters are strongly correlated to health-related and neurobehavioral outcomes in youth with T1DM. This suggests that improving sleep might reduce morbidity. A critical step in developing evidence-based guidelines regarding sleep in diabetes management is to first determine that sleep modification in natural settings is possible (i.e., instructing youth to have a healthy sleep opportunity leads to more total sleep time) and that an increased sleep duration impacts disease and psychosocial outcomes in these youth. This article describes the background, design, and feasibility of an ongoing randomized clinical trial that aims to examine if increasing sleep relative to youth's own sleep routines affects glucose control and daytime functioning.

A randomized trial of adenotonsillectomy for childhood sleep apnea

BACKGROUND

Adenotonsillectomy is commonly performed in children with the obstructive sleep apnea syndrome, yet its usefulness in reducing symptoms and improving cognition, behavior, quality of life, and polysomnographic findings has not been rigorously evaluated. We hypothesized that, in children with the obstructive sleep apnea syndrome without prolonged oxyhemoglobin desaturation, early adenotonsillectomy, as compared with watchful waiting with supportive care, would result in improved outcomes.

METHODS

We randomly assigned 464 children, 5 to 9 years of age, with the obstructive sleep apnea syndrome to early adenotonsillectomy or a strategy of watchful waiting. Polysomnographic, cognitive, behavioral, and health outcomes were assessed at baseline and at 7 months.

RESULTS

The average baseline value for the primary outcome, the attention and executive-function score on the Developmental Neuropsychological Assessment (with scores ranging from 50 to 150 and higher scores indicating better functioning), was close to the population mean of 100, and the change from baseline to follow-up did not differ significantly according to study group (mean [±SD] improvement, 7.1±13.9 in the early-adenotonsillectomy group and 5.1±13.4 in the watchful-waiting group; P=0.16). In contrast, there were significantly greater improvements in behavioral, quality-of-life, and polysomnographic findings and significantly greater reduction in symptoms in the early-adenotonsillectomy group than in the watchful-waiting group. Normalization of polysomnographic findings was observed in a larger proportion of children in the early-adenotonsillectomy group than in the watchful-waiting group (79% vs. 46%).

CONCLUSIONS

As compared with a strategy of watchful waiting, surgical treatment for the obstructive sleep apnea syndrome in school-age children did not significantly improve attention or executive function as measured by neuropsychological testing but did reduce symptoms and improve secondary outcomes of behavior, quality of life, and polysomnographic findings, thus providing evidence of beneficial effects of early adenotonsillectomy. (Funded by the National Institutes of Health; CHAT ClinicalTrials.gov number, NCT00560859.).

Functional neuronal network activity differs with cognitive dysfunction in childhood-onset systemic lupus erythematosus

Introduction

Neuropsychiatric manifestations are common in childhood-onset systemic lupus erythematosus (cSLE) and often include neurocognitive dysfunction (NCD). Functional magnetic resonance imaging (fMRI) can measure brain activation during tasks that invoke domains of cognitive function impaired by cSLE. This study investigates specific changes in brain function attributable to NCD in cSLE that have potential to serve as imaging biomarkers.

Methods

Formal neuropsychological testing was done to measure cognitive ability and to identify NCD. Participants performed fMRI tasks probing three cognitive domains impacted by cSLE: visuoconstructional ability (VCA), working memory, and attention. Imaging data, collected on 3-Tesla scanners, included a high-resolution T1-weighted anatomic reference image followed by a T2*-weighted whole-brain echo planar image series for each fMRI task. Brain activation using blood oxygenation level-dependent contrast was compared between cSLE patients with NCD (NCD-group, n = 7) vs. without NCD (noNCD-group, n = 14) using voxel-wise and region of interest-based analyses. The relationship of brain activation during fMRI tasks and performance in formal neuropsychological testing was assessed.

Results

Greater brain activation was observed in the noNCD-group vs. NCD-group during VCA and working memory fMRI tasks. Conversely, compared to the noNCD-group, the NCD-group showed more brain activation during the attention fMRI task. In region of interest analysis, brain activity during VCA and working memory fMRI tasks was positively associated with the participants' neuropsychological test performance. In contrast, brain activation during the attention fMRI task was negatively correlated with neuropsychological test performance. While the NCD group performed worse than the noNCD group during VCA and working memory tasks, the attention task was performed equally well by both groups.

Conclusions

NCD in patients with cSLE is characterized by differential activation of functional neuronal networks during fMRI tasks probing working memory, VCA, and attention. Results suggest a compensatory mechanism allows maintenance of attentional performance under NCD. This mechanism appears to break down for the VCA and working memory challenges presented in this study. The observation that neuronal network activation is related to the formal neuropsychological testing performance makes fMRI a candidate imaging biomarker for cSLE-associated NCD.

Association of daytime somnolence with executive functioning in the first 6 months after adolescent traumatic brain injury

OBJECTIVE

To determine the relationship between severity of injury and self-reports and parent reports of daytime somnolence in adolescents after traumatic brain injury (TBI), and to determine the relationship between daytime somnolence and self-report and parent report of executive functioning in daily life.

DESIGN

Cross-sectional study conducted within the first 6 months (mean ± standard deviation 14.97 ± 7.51 weeks) after injury. Partial correlation controlling for injury severity was used to examine the associations of TBI severity with daytime somnolence and the association of daytime somnolence with executive functioning.

SETTING

Outpatient visits at 3 children's hospitals and 2 general hospitals with pediatric trauma commitment.

PARTICIPANTS

A total of 102 adolescents, 12-18 years old, who sustained moderate-to-severe TBI (n = 60) or complicated mild TBI (n = 42).

MAIN OUTCOME MEASUREMENTS

Parent-report Sleepiness Scale, Epworth Sleepiness Scale (youth report), Behavior Rating Inventory of Executive Function (BRIEF) (self-report and maternal report).

RESULTS

Adolescents who sustained moderate-to-severe TBI had increased daytime somnolence compared with those with complicated mild injuries in the parent report but not in the youth report. Based on the parent report, 51% of adolescents with moderate-to-severe TBI showed significant daytime somnolence compared with 22% of those with complicated mild TBI. The parent report of daytime somnolence was associated with executive dysfunction on both the BRIEF self-report and parent report; however, the youth report of daytime somnolence was associated only with the BRIEF self-report.

CONCLUSIONS

The parent report of daytime somnolence correlated with TBI severity and predicted executive functioning difficulties of the teens in everyday circumstances. Although a correlation between daytime somnolence and executive dysfunction were also apparent on self-report, this did not differ based on injury severity. Teens tended to report fewer difficulties with executive function, which suggests that the teens have decreased awareness of their impairments.

Academic outcomes in childhood-onset systemic lupus erythematosus

OBJECTIVE

To explore academic outcomes in childhood-onset systemic lupus erythematosus (cSLE) and their relationship to variables such as demographic and socioeconomic status, neurocognitive functioning, behavioral/emotional adjustment, and cSLE disease status.

METHODS

Forty pairs of children diagnosed with cSLE and healthy best friend controls were rated by parents on a standardized scale of school competence. Information about participants' demographic and socioeconomic status was obtained, along with measures of cSLE disease activity and damage. All of the participants received formal neurocognitive testing and were also rated on standardized scales of behavioral/emotional adjustment and executive functioning.

RESULTS

Compared to healthy controls, school competence was rated as lower in the cSLE group, although the groups did not differ significantly on indices of cognitive, behavioral, emotional, or executive functioning. School competence ratings were correlated with reading and mathematics achievement test scores in both groups, and with ratings of mental self-regulation in the cSLE group. School competence ratings were correlated with measures of cSLE disease activity and treatment intensity.

CONCLUSION

cSLE is associated with inferior parent-rated academic outcomes compared to those noted in demographically-matched peers, despite similar neurocognitive function. The adverse academic outcomes that distinguish children with cSLE from their demographically-matched peers appear to be mediated by SLE disease activity and treatment.

The Childhood Adenotonsillectomy Trial (CHAT): rationale, design, and challenges of a randomized controlled trial evaluating a standard surgical procedure in a pediatric population

Each year, over 500,000 adenotonsillectomies (AT), mostly for the treatment of pediatric obstructive sleep apnea (OSA) are performed in the US in children under 15 years of age. No definitive study, however, has been yet conducted that has rigorously evaluated the effectiveness of AT for not only improving sleep disordered breathing, but also for improving clinically relevant outcomes, such as neurocognitive function, behavior, and quality of life. The Childhood Adenotonsillectomy Trial (CHAT) was designed to assess neuropsychological and health outcomes in children randomized to receive early AT (eAT) as compared to Watchful Waiting with Supportive Care (WWSC). Important secondary goals of the study are to evaluate outcomes in subgroups defined by obesity and race. This paper addresses key elements in the design and implementation of a controlled trial for a widely used "standard practice" surgical intervention in a pediatric population, that include establishment of standardized data collection procedures across sites for a wide variety of data types, establishment of equipoise, and approaches for minimizing unblinding of selected key personnel. The study framework that was established should provide a useful template for other pediatric controlled studies or other studies that evaluate surgical interventions.

Psychometric support for an abbreviated version of the Behavior Rating Inventory of Executive Function (BRIEF) Parent Form

The objectives of this study were to systematically develop and evaluate the psychometric properties of an abbreviated version of the Behavior Rating Inventory of Executive Function (BRIEF) Parent Report; a questionnaire widely used by pediatric neuropsychologists. A total of 24 items from the original BRIEF Parent Form were selected for the short-form, which was then evaluated in three complementary samples, according to six a priori psychometric criteria. The short-form generally demonstrated appropriate psychometric qualities, with convincing evidence for the reliability and validity of the three composite indices: Behavioral Regulation, Metacognition, and the Global Executive Composite. Potential clinical applications include screening at-risk children in medical clinics to facilitate appropriate referrals for further psychological consultation. In research settings, the short-form can be easily integrated into studies involving mass collection of data (e.g., large-scale epidemiological research), facilitating advancements in the scientific understanding of neuropsychological morbidity in medically involved populations.

A review of the effects of sleep during the first year of life on cognitive, psychomotor, and temperament development

During the first year of life, infants spend most of their time in the sleeping state. Assessment of sleep during infancy presents an opportunity to study the impact of sleep on the maturation of the central nervous system (CNS), overall functioning, and future cognitive, psychomotor, and temperament development. To assess what is currently known regarding sleep during infancy and its effects on cognitive, psychomotor, and temperament development, we assessed the relevant literature published over the last several decades. To provide a foundation for a more in-depth understanding of this literature, we preface this with an overview of brain maturation, sleep development, and various assessment tools of both sleep and development during this unique period. At present, we do not have sufficient data to conclude that a causal relationship exists between infant sleep and cognitive, psychomotor, and temperament development. Caution should be used in predicting outcomes, as the timing and subjectivity of evaluations may obviate accurate assessment. Collectively, studies assess a wide array of sleep measures, and findings from one developmental period cannot be generalized readily to other developmental periods. Future studies should follow patients longitudinally. Additionally, refinements of existing assessment tools would be useful. In view of the relatively high reported pediatric prevalence of cognitive and behavioral deficits that carry significant long-term costs to individuals and society, early screening of sleep-related issues may be a useful tool to guide targeted prevention and early intervention.

Working with the Relational World of the Preschool Child using Psychodynamic Group Therapy

For over forty years, Bellevue Hospital's Therapeutic Nursery Program has been addressing the emotional problems of New York City preschoolers, aged two to five years, with the help of their families and other caregivers. Typical psychiatric disorders treated in the Therapeutic Nursery Program include anxiety disorders (separation anxiety, generalized anxiety and posttraumatic stress disorder), disruptive behavior disorders (attention deficit hyperactivity disorder and oppositional defiant disorder), mood disorders, adjustment disorders and attachment disorders.

We have found that group psychotherapy provides a safe and secure place where, through psychodynamic intervention, children can repair dysfunctional relationships, identify and express a full range of emotions, resolve cultural differences and develop age appropriate skills.

Our Therapeutic Nursery Program employs a wide range of additional treatment modalities in order to reach the treatment goals. Individual or family sessions, as well as meetings with teachers and social service workers, are scheduled to address issues.

We have also found that dyadic or sibling work is often needed to stop or reverse the development of inappropriate family relationships.

One of our indications of a successful intervention is that either during or after their participation in the Therapeutic Nursery, children return to community-based daycare centers and preschools. We have also found that via participation in the Therapeutic Nursery program, families have opportunities to strengthen their ability to nurture their children, share successful parenting with other families and build pleasurable experiences with their children.

Factors of biological risk and reserve associated with executive behaviors in children and adolescents with spina bifida myelomeningocele

This study examined differences between healthy children (n = 35) and those with spina bifida myelomeningocele (SBM; n = 42) on the Behavior Rating Inventory of Executive Function (BRIEF), a measure of executive function behaviors. It also examined whether aspects of biological risk associated with SBM and reserve factors within the family could account for variability in BRIEF scores for children and adolescents with SBM. Patients in the SBM group exhibited more problems than both published norms and a local comparison group of healthy children in metacognition but not behavior regulation. Behavior regulation problems in children with SBM were predicted by parent psychological distress. More shunt-related surgeries and history of seizures predicted poorer metacognitive abilities.

5 ASSESSMENT OF HSP70.1 TRANSCRIPTION LEVELS IN BOVINE EMBRYOS AFTER CUMULUS REMOVAL BY DIFFERENT TECHNIQUES

Previous results indicated that there was a difference in transcriptional activity depending on the method used to remove the cumulus cells after IVF (Zeringue et al. 2005 LabChip 5, 86-90). However, specific gene expression was not examined and therefore was the goal of the present study. The objective of this study was to compare the transcription levels of the HSP70.1 gene in bovine in vitro production (IVP) embryos that underwent cumulus removal by vortexing, hand stripping, or microfluidic treatment. Quantitative real-time PCR was used to estimate transcription levels of the HSP70.1 gene in bovine IVP zygotes and two-cell embryos. Transcription levels were compared between embryos that underwent three methods of cumulus removal. Presumptive zygotes were harvested at 2 or 24 h after cumulus removal by vortexing, by hand stripping, or by microfluidic means in order to compare the relative embryonic stress of these three treatments. Bovine in vitro embryos were produced by standard means with the only variable being the cumulus removal technique 24 h after fertilization. At 2 and 24 h post-cumulus removal, randomly selected presumptive zygotes were taken out of culture, preserved in RNAlater (Ambion, Inc., Austin, TX, USA) and stored at -20�C. RNA was extracted from single embryos via Qiagen's RNeasy Micro kit (Valencia, CA, USA). RNA was amplified and PCR products were detected with SYBR Green 1 (Applied Biosystems, Foster City, CA, USA) using an Opticon Monitor 3 real-time PCR machine (Bio-Rad Laboratories, Inc., Waltham, MA, USA). The threshold cycle (CT) numbers were determined for the amplified cDNA of the bovine HSP70.1 mRNA and for the housekeeping gene, acidic ribosomal phosphoprotein (PO), used as a reference. Then the amount of HSP70.1 was divided by the amount of PO to obtain a normalized HSP70.1 value expressed as the ratio of HSP70.1/PO. Ratios were analyzed by the GENMOD procedure in SAS (SAS Institute, Inc., Cary, NC, USA) accounting for replicates and treatments. Transcription levels of the HSP70.1 gene did not differ significantly between the microfluidically treated and vortexed groups of zygotes at 2 h post-cumulus removal (P = 0.1032) or between the hand-stripped and vortexed groups (P = 0.7567). In contrast, at 24 h post-cumulus removal, the embryos in the microfluidically treated group showed significantly higher levels of HSP70.1 transcription than the vortexed group (P = 0.0115). The transcription levels did not differ significantly between the hand-stripped and vortexed groups (P = 0.7875). This work strongly suggests that there is de novo RNA transcription in the early embryonic stages of the bovine. In addition to previously described improved developmental kinetics, the use of microfluidics in IVP leads to statistically significant differences in RNA transcription levels of HSP70.1.

156 ENHANCED BOVINE EMBRYONIC DEVELOPMENT AFTER MICROFLUIDIC CUMULUS CELL REMOVAL POST-FERTILIZATION

Microfluidic technologies are increasingly being used in cell biology and embryology research. In order to manipulate an embryonic environment microfluidics take advantage of miniscule media amounts. With the use of pressure heads and laminar flow profiles, a presumptive zygote can be gently manipulated in a microfluidic device for removal of the supporting cumulus cells post-fertilization. Presumptive embryos were assigned at random to three cumulus removal treatments at 48 h post-fertilization: vortexing (3 min), handstripping (with 135-μm-ID stripping pipette), and microfluidics. Blastocyst rates were determined through Day 8 post-fertilization. Rates were analyzed by the GENMOD procedure in SAS (SAS Institute, Inc., Cary, NC, USA), accounting for replicates and treatment. Kinetics of development were also impacted as larger proportions of embryos in the microfluidic group reached the blastocyst stage before embryos of the vortex or hand-stripping treatments. These data suggest that cumulus cell removal in a gentle fashion is associated with enhanced embryonic development in the bovine. Table 1. Comparison of cumulus cell removal techniques on bovine blastocyst rates

Sleep in Individuals With Angelman Syndrome: Parent Perceptions of Patterns and Problems

The diagnostic criteria for Angelman syndrome includes sleep disturbance as an associated characteristic. There are, however, few researchers who have examined sleep problems in this population. Our goal in this study was to better characterize the sleep patterns and problems in individuals with Angelman syndrome. Parents of 339 individuals between the ages of 3 and 22 completed a previously validated sleep questionnaire. Results confirmed that a variety of sleep problems exist in a significant portion of individuals with Angelman syndrome, most prominently in the areas of sleep initiation, sleep duration, reliance on sleep facilitators, being awakened by loud noises, and being disoriented when aroused. Developmental trends, syndrome specificity of findings, clinical implications, and directions for future research are discussed.

Microfluidic technology for assisted reproduction

The physical tools used in assisted reproduction have changed little over several decades. Microfluidics is an emerging technology that allows a fresh examination of the way assisted reproduction is performed. Here we review our work to develop microfluidic devices to perform the functions required in assisted reproduction. These functions include loading/unloading, culture, chemical manipulation, and mechanical manipulation of embryos and oocytes. Basic microfluidic theory and microfluidic device design and operation are discussed. Results are presented for mechanical removal of cumulus cells and for embryo culture. Results suggest that microfluidic systems will lead to improved efficiencies in assisted reproduction.

The SCARFACE gene is required for cotyledon and leaf vein patterning

Mechanisms controlling vein patterning are poorly understood. We describe a recessive Arabidopsis mutant, scarface (sfc), which maps to chromosome 5. sfc mutants have vein pattern defects in cotyledons, leaves, sepals and petals. In contrast to the wild type, in which these organs all have linear veins that are continuous with at least one other vein, in sfc mutants these organs' secondary and tertiary veins are largely replaced by small segments of discontinuous veins, which we call vascular islands. Patterning defects are manifest in cotyledon provascular tissue, suggesting that the patterning defect occurs early in organogenesis. sfc mutants have exaggerated responses to exogenous auxin. Analysis of monopteros (mp(T370)) sfc-1 double mutants suggested that SFC has partially overlapping functions with MP in patterning of both primary and secondary veins.

Normalizing mitochondrial superoxide production blocks three pathways of hyperglycaemic damage

Diabetic hyperglycaemia causes a variety of pathological changes in small vessels, arteries and peripheral nerves. Vascular endothelial cells are an important target of hyperglycaemic damage, but the mechanisms underlying this damage are not fully understood. Three seemingly independent biochemical pathways are involved in the pathogenesis: glucose-induced activation of protein kinase C isoforms; increased formation of glucose-derived advanced glycation end-products; and increased glucose flux through the aldose reductase pathway. The relevance of each of these pathways is supported by animal studies in which pathway-specific inhibitors prevent various hyperglycaemia-induced abnormalities. Hyperglycaemia increases the production of reactive oxygen species inside cultured bovine aortic endothelial cells. Here we show that this increase in reactive oxygen species is prevented by an inhibitor of electron transport chain complex II, by an uncoupler of oxidative phosphorylation, by uncoupling protein-1 and by manganese superoxide dismutase. Normalizing levels of mitochondrial reactive oxygen species with each of these agents prevents glucose-induced activation of protein kinase C, formation of advanced glycation end-products, sorbitol accumulation and NFkappaB activation.

The expression pattern of a novel Deltex homologue during chicken embryogenesis

We isolated a partial cDNA encoding a novel chicken homologue of human Deltex (DTX1), a member of the Notch signaling pathway. The cDtx2 sequence showed higher homology to KIAA0937 protein (92% identical) than to DTX1 (68% identical). cDtx2 is expressed widely in the epiblast at stage 4. Later in development it is expressed in many neural and sensory structures, such as neural tube, migrating neural crest cells, epidermal placodes, cranial ganglia, and the optic and otic vesicles.

Combined liver-total bowel transplantation has no immunologic advantage over total bowel transplantation alone. A prospective study in a porcine model

BACKGROUND

Rejection remains a major obstacle to successful bowel transplantation in humans. It has been suggested that a simultaneous liver transplant would shield the bowel graft from immunologic attack, but the liver shortage would be aggravated. In a preclinical model, we studied the influence of simultaneous liver grafting by comparing the incidence of early bowel rejection after combined liver-total (small- and large-) bowel transplants vs total bowel transplants alone.

METHODS

We assessed the incidence of early post-transplant rejection, graft-vs-host disease, and infection after combined liver-total bowel transplants (group 1, n = 10) and total bowel transplants alone (group 2, n = 9) in outbred Yorkshire Landrace pigs. Liver and bowel grafts were transplanted orthotopically with portal vein drainage after recipient hepatectomy (group 1) and total enterectomy (groups 1 and 2). Posttransplant immunosuppression was performed with intravenous tacrolimus (whole blood levels, 15 to 30 ng/mL) and prednisolone. In groups 1 and 2, bowel biopsy specimens from the ileostomy were obtained daily. In group 1, liver biopsy specimens were obtained weekly. Rejection was graded according to a 4-point scoring system (none, mild, moderate, and severe).

RESULTS

Overall graft survival at days 7, 14, and 21 was 89%, 44%, and 11%, respectively, in group 1 vs 100%, 100%, and 86%, respectively, in group 2 (P < .001). Death rates owing to (irreversible) rejection at days 7, 14, and 21 were 0% in groups 1 and 2 (P = .48). Grading of bowel rejection episodes, based on the results of daily biopsy specimens, was not significantly different between the groups whether on individual days or overall. In group 1, the incidence of liver rejection episodes was as high as 66% (day 14 and at autopsy). At autopsy, generalized graft-vs-host disease (skin, native intestine, and native liver) was noted in 55% of group 1 and 43% of group 2 pigs (P = .55). Graft-vs-host disease was noted concurrently with rejection episodes of the liver or bowel grafts.

CONCLUSIONS

Simultaneous liver grafting did not further reduce the incidence of early bowel rejection or graft-vs-host disease when compared with total bowel transplants alone. Based on the results of this preclinical study, simultaneous liver grafting is not indicated for patients with short-bowel syndrome and normal liver function.

Quadruple immunosuppression in a pig model of small bowel transplantation

Rejection remains a major obstacle to successful small bowel transplantation in humans, irrespective of the immunosuppressants. Previous large animal studies have not used quadruple immunosuppression (with high-dose intravenous cyclosporine A [CSA]) for induction, followed by triple immunosuppression for maintenance therapy. Nor have immunosuppressive doses been comparable to clinical solid organ transplants. We studied, in 78 nonrelated outbred pigs, the effect of quadruple immunosuppression (including horse anti-pig thymocyte globulin [ATG] and high-dose intravenous CSA) on the incidence and severity of rejection in the early, critical posttransplant period. Group A (n = 19) pigs were nonimmunosuppressed. Group B (n = 20) received quadruple immunosuppression: pig ATG (10 mg/kg/day x 10 days), intravenous CSA (3.0 mg/kg/day), prednisolone (2 mg/kg/day), and azathioprine (2.5 mg/kg/day); prednisolone and azathioprine were each reduced by 50% on posttransplant Days 8 and 15. Trough CSA levels were > or = 400 ng/ml for the first 7 days posttransplant, > 200 ng/ml thereafter. Recipient pigs underwent resection of large and small bowel; orthotopic transplants (proximal duodenojejunostomy, distal ileostomy) were done with systemic vein drainage. We developed a scoring system (no, mild, moderate, severe rejection) to grade the extent of both interstitial and vascular rejection: biopsies were obtained daily from the ileostomy. Rejection-free graft survival at posttransplant Days 7, 10, and 14 was 32, 26, and 16% in the nonimmunosuppressed group versus 95, 90, and 85% in the immunosuppressed group (P < 0.0001). Rejection grades were significantly better over the whole observation period in immunosuppressed pigs: interstitial rejection was not present in up to 67% of all daily biopsy specimens. Rejection was present in all specimens of nonimmunosuppressed pigs. Vascular rejection was uncommon (incidence < 10%) in both groups. Isolated vascular rejection without interstitial rejection was not found. Graft-versus-host reaction was noted in both groups in the skin only; liver and native bowel were not involved. We conclude that quadruple immunosuppression with pig ATG and high-dose intravenous CSA for induction effectively prevents moderate and severe rejection in this model. Since clinical transplant complications (rejection, lymphomas) have persisted under FK 506 treatment, our immunosuppressive regimen should be considered an alternative for bowel transplantation in humans to prevent early rejection.

Residents' formal knowledge acquisition and preferred learning styles

BACKGROUND

Many family practice residency programs use the Myers-Briggs Type Indicator (MBTI) in their educational programs. Our purpose was to study the relationship between learning style, as determined by MBTI personality preferences, and residents' cognitive knowledge acquisition, measured by in-service training examination (ISTE) scores during the first and third years of residency.

METHODS

We evaluated 36 residents using both their first- and third-year ISTE composite scores and their MBTI scores. ISTE scores were analyzed according to the MBTI personality factors. We used the Wilcoxon Rank-Sum Test to determine the association between the improvement in residents' ISTE scores between the first- and third-year examinations and preferred learning styles.

RESULTS

Significant differences were found on the composite ISTE scores for the thinking/feeling and judgment/perception scales. Feelers increased ISTE scores more than thinkers (P = .031); judgers increased ISTE scores more than perceivers (P = .04).

CONCLUSIONS

Results do not support the literature or current MBTI learning theory. Intuitive residents demonstrated no advantage over sensing residents. Residents using feeling/judgment as their preferred learning style acquired more knowledge over 3 years than their thinking/perceiving counterparts, as measured by ISTE scores.

c-myc mRNA is elevated as differentiating lens cells withdraw from the cell cycle

Explants of the central region of lens epithelia from early chicken embryos differentiate in vitro to form lens fiber cells when cultured in the presence of chicken vitreous humor. Hybridization of a 32P-labeled v-myc viral oncogene DNA probe to RNA extracted from differentiating explants and immobilized on nitrocellulose filters indicates that levels of 2.5 kb c-myc mRNA are transiently elevated 5-10-fold in the differentiating cells. Increased levels of c-myc mRNA are observed within 30 min of the initiation of differentiation in vitro and persist for 8-9 h. Thymidine labeling of nuclei in differentiating explants indicates that entry of cells into S phase is inhibited during this period, as differentiating cells complete a final round of mitosis and withdraw from the cell cycle. Levels of c-myc mRNA are also elevated in the peripheral region of the lens epithelium, which contains cells undergoing differentiation in vivo, suggesting that the regulation of c-myc mRNA which occurs in vitro may also occur in vivo. c-myc mRNA, c-fos mRNA, and c-src mRNA showed distinct patterns of regulation associated with lens fiber formation in vivo, thus providing evidence that the regulation of c-myc mRNA is specific to this proto-oncogene. The finding that c-myc mRNA undergoes a specific, transient elevation in differentiating lens cells as they withdraw from the cell cycle contrasts with a large body of evidence linking enhanced c-myc expression with increased cell proliferation.

Binding interaction studies of selected receptor subpopulations after partial cross-linking receptor-ligand complexes with a photoactivated heterobifunctional reagent

Certain hormonal and nonhormonal binding systems such as the leukoagglutinin-lymphocyte model exhibit complex receptor-ligand interactions that result in nonlinear Scatchard plots. Such plots are interpreted as indicating either homogeneous negatively interacting binding sites or heterogeneous sites with different and fixed affinity. We assessed the validity of these interpretations in our system by conjugating the ligand to a photoactivated heterobifunctional agent and cross-linking the conjugate to a subset of receptors before studying the binding interactions of non-cross-linked sites. Conjugation did not qualitatively or quantitatively affect the binding properties of the ligand. Cross-linking was specific, efficient, and stable and had no effect on irrelevant surface receptors. Cross-linking of only 3% of the total receptors resulted in 50% decreased ligand binding to high affinity sites consistent with a calculated inactivation of 85% and 2% of high and low affinity sites, respectively. Such preferential inactivation of high affinity sites in an unequivocal demonstration of binding sites heterogeneity in this system and shows a clear rejection of the homogeneous cooperation model.

C5 chemotactic fragment induces leukocyte production of tissue factor activity: a link between complement and coagulation

Complement-activated human plasma causes generation of tissue factor in human leukocytes. This phenomenon appears to be related to the fifth component of complement (C5) as demonstrated by the use of C5 deficient-plasma and suppression of activity with antibody to C5. Isolation of the chemotactic factor from activated serum or trypsinization of purified C5 reproduces the phenomenon. These data provide evidence for a direct link between complement products and activation of the coagulation system. Because chemotactic peptides from C5 can be generated by a variety of enzymes, our findings suggest a relationship between complement, coagulation, and inflammation.

The C5 Chemotactic Fragment Isolated from Activated Human Serum

A chemotactic factor for rabbit and human polymorphonuclear leukocytes antigenically related to C5 has been isolated from human serum activated by zymosan in the presence of ε-amino caproic acid (EACA). Antiserum to the purified chemotactic factor as well as antiserum to human C5, inhibitis the chemotactic activity in human serum activated by zymosan, aggregated IgG, immune complexes, or bacterial lipopolysaccharide. The chemotactic activity of bacterial (E. coli) factor is not inhibited by either antiserum. The C5 chemotactic factor is purified by a combination of gel filtration and ion exchange gel chromatography. Analysis for anaphylatoxin activity in fractions from each step of the procedure indicates that the muscle-contracting activity is separated from the bulk of the chemotactic activity in the anion exchange step. The purified chemotactic factor migrates as an α globulin as assessed by elution activity in agarose.